Cosmonauts walk after NASA rebuffs space tourist

(CNN) -- NASA managers at the Johnson Space Center in Houston rebuffed a training visit by prospective space tourist Dennis Tito Monday, prompting him and his Russian cosmonaut crewmates to leave the facility in a huff.

The incident is a serious blow to the already tense, tenuous space partnership between the United States and Russia to build international space station Alpha.

The Russian Aeronautics and Space Agency (Rosaviakosmos) is insisting Tito fly to Alpha on a Soyuz rocket April 30 for a week-long visit. But NASA is steadfastly opposing the idea -- saying it is premature to consider citizen travelers to the outpost.

During a series of high-level meetings between the partners in recent weeks, the Russians agreed, in principle, to create -- and adhere to -- a series of guidelines to determine who should be allowed to visit the station. But NASA officials said their Russian counterparts have insisted an exception be made for Tito.

The California investment adviser and former NASA engineer initially offered $20 million for a stay at the Russian Space Station Mir. When that deal unraveled, he cut a similar deal for a trip to Alpha on a routine mission to dock a new Soyuz to the budding outpost.

"This is about Dennis Tito, not the greater issue of space tourism," said NASA astronaut and manager Bill Readdy. " We are not going to let him be the wedge to drive us apart."

The incident occurred as the crew of the so-called Soyuz "taxi" mission arrived at JSC for five days of training on U.S. systems on Alpha. Tito, along with his two prime cosmonaut crewmates and two backups, arrived at the visitor center at the edge of NASA's fenced campus to obtain their security badges.

The group was escorted into a conference room where NASA astronaut and space station manager Bob Cabana broke the news that Tito would not be participating in the training schedule - instead attending a series of meetings with space agency lawyers and a tour of the space center.

At that point, Tito's commander, Talgat Musabayev, insisted that his crew would remain intact for training.

When Cabana expressed NASA's decision that it is not willing to train Tito now, the visitors departed hastily -- returning to their hotels.

"It was a definite breach," said Newsweek senior editor David France, who accompanied Tito and his party. Nevertheless he described the exchange as cordial.

NASA managers said they believe civilians could pose a safety threat in orbit.

"The [U.S.S.] Greeneville incident points out the unintentional consequences of non-professional people being in inherently hazardous operations," said Readdy.

The Russians have committed to supplying a new Soyuz spacecraft to the $100 billion station every six months. They are interested in routinely selling one of the three seats to well-heeled travelers with a taste for adventure.

The Alpha station is a 16-nation project led by NASA and the Russians. It has been occupied since November 2, 2000. The second live-in US/Russian crew began its four-month tour of duty this week.